[time-nuts] Aircraft ping timing

Brooke Clarke brooke at pacific.net
Wed Mar 19 21:36:47 EDT 2014


Hi Antonio:

It's my understanding that the satellite sends a ping to each aircraft in it's low gain antenna pattern once every hour 
by aircraft ID number.
The aircraft replies with a very short data packet that's time stamped (but without any location or other info other 
than the ID).
The difference between the time stamp on the ping and the received message is the ping time.
The idea is to have some idea which of the spot beams to use if someone on the plane wanted to make a phone call.
As it happens MH370 does not have first class or sat phones, but this is the default system for everyone.

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

iovane at inwind.it wrote:
>> ----Messaggio originale----
>> Da: jfor at quikus.com
>> Data: 20/03/2014 1.47
>>
>> It depends on how accurately the bird can measure the round-trip time:
>>
>> 1 us  = ca 500'
>> 10 us = ca 1 mile
>> 100us = ca 10 miles
>> 1 ms  = ca 100 miles
>>
>> The arcs are loci of constant round trip time, projected on the globe.
> This is valid for round trip and for the signal path which in this case is the
> line generating the cone having the bird at its apex. The radius of the circle
> at earth is another thing, and the error should be multiplied by some factor
> which depends on the angle at the apex, being the earth's surface curve. Hence
> I tought that the timing is crucial. Add to this that I understood it was not a
> ping as we usually mean, but a one way signal (aircraft to satellite). Hence my
> question.
>
> Antonio I8IOV
>> -John
>>
>> ===============
>>
>>
>>
>>
>>> My question was on what would be the expected accuracy of the circle's
>>> radius.
>>>
>>> Antonio I8IOV
>>>
>>>> ----Messaggio originale----
>>>> Da: bill at iaxs.net
>>>> Data: 20/03/2014 1.21
>>>>
>>>> They only got one ping from INMARSAT at 64E above the Indian Ocean.
>>>> There was no other ping to triangulate the position.
>>>>
>>>> One ping projects a circle on the Earth. The maximum flying range of the
>>>> plane determined the ends of the NE and SE arcs of that circle.
>>>>
>>>> The news only gets stranger as time goes on.
>>>>
>>>> Bill Hawkins
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: iovane at inwind.it
>>>> Sent: Wednesday, March 19, 2014 6:46 PM
>>>>
>>>> Those who say the missing aircraft should be searched along the two
>>>> corridors, what measurement are they relying on? I think it is a one-way
>>>> measurement of time-stamped pings, which implies good synchronization of
>>>> clocks between a geosynchronous satellite and a moving aircraft. Antonio
>>>> I8IOV
>>>>
>>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>>
>>
>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



More information about the time-nuts mailing list